1. Field of the Invention
The present invention relates to an optical information recording medium, and particularly to a rewritable phase-change optical information recording medium for use as a CD-RW, DVD−RW, DVD+RW, etc. In addition, the present invention relates to a recording method and apparatus in which information is recorded in the optical information recording medium. Further, the present invention relates to an information recording method in which information is overwritten in the optical information recording medium. Furthermore, the present invention relates to an information erasing method.
2. Discussion of the Related Art
Conventional CD-RWs include a guide groove. As illustrated in FIG. 8, the guide groove is wobbled because wobble signals are recorded on entire the surface thereof in an irradiation process in stamping.
The wobble signals include time (address) information called ATIP (absolute time in pre-groove). ATIP is represented as, for example, “00m00s00f”, wherein m represents minute, s represents second and f represents flame (i.e., 1/75 second). In an area located before the point 00m00s00f, a PMA (program memory area) is present. In an area located between the PMA and the point 00m00s00f, “special information” and “additional information” which are important information concerning record/reproduction of the optical recording medium are recorded.
“Multi-session” is one of the file structures of rewritable optical information recording media and means a structure in which two or more sessions are recorded in an optical information recording medium. Each session includes a lead-in area (hereinafter sometimes referred to as a L/I or a L/I area), a data area (hereinafter sometimes referred to as a Data or a Data area) and a lead-out area (hereinafter sometimes referred to as a L/O or a L/O area).
FIGS. 1 and 2A-2F are schematic views illustrating data arrangement in conventional CD-RWs.
FIG. 1 is a schematic view illustrating arrangement of address data of a conventional CD-RW. Referring to FIG. 1, the area of from a point of 98m13s50f to a point of 98m27s00f is a program memory area (hereinafter sometimes referred to as a PMA). The area of from a point of 98m27s00f to a point of 99m59s74f is a L/I area. The area of from a point of 00m00s00f to a point of 75m42s00f is a Data area.
FIG. 2A is a schematic view illustrating a state of a CD-RW in which information is not recorded (i.e., a state of a CD-RW which is not used).
FIG. 2B is a schematic view illustrating a state of the CD-RW, in which a first session (i.e., L/I-1, Data-1 and L/O-1) is recorded in the CD-RW illustrated in FIG. 2A. In this case, information of disc ID D and first session position information 1 are recorded in this order from the inside of the PMA.
FIG. 2C is a schematic view illustrating a state of the CD-RW, in which a second session (i.e., L/I-2, Data-2 and L/O-2) is recorded in the CD-RW illustrated in FIG. 2B. In this case, the information of disc ID D, the first session information 1 and second session position information are recorded in this order from the inside of the PMA.
Information recorded in a phase change optical information recording medium can be erased. For example, all information recorded in a medium can be erased at once or only the last session of multiple sessions of a medium can be erased. At this point, erasure of information is performed by recording erasure signals.
FIG. 2D is a schematic view illustrating a state of the CD-RW, in which the last session (i.e., the second session) of the CD-RW illustrated in FIG. 2C is erased.
FIG. 2E is a schematic view illustrating a state of the CD-RW, in which the last session (i.e., the first session) of the CD-RW illustrated in FIG. 2D is erased. This state is logically the same as the state illustrated in FIG. 2A, however, they are different because erasure signals are recorded in the CD-RW illustrated in FIG. 2E whereas information is not recorded in the CD-RW illustrated in FIG. 2A.
FIG. 2F is a schematic view illustrating a state of the CD-RW in which all information is erased. This state is logically the same as the state illustrated in FIG. 2A, however, they are different because erasure signals are recorded in the CD-RW illustrated in FIG. 2F.
Recently, recordable optical information recording media having a ROM region, such as CD-Rs and CD-RWs, have been proposed. As one of the recordable optical information recording media, optical information recording media having a multi-session structure in which the first session is a ROM region including pits have been proposed.
A recording medium illustrated in FIGS. 3A to 3F is the same as that illustrated in FIGS. 2A to 2E except that the first session is a ROM region including pits.
FIG. 3A illustrates a CD-RW which is not used and which has a ROM region in which signals (L/I-1, Data-1 and L/O-1) are recorded by pits.
In the ROM region, pits and the groove formed between the pits are wobbled as illustrated in FIG. 9 to obtain wobble signals similarly to the signals in the RAM region.
FIG. 3B illustrates a state of the CD-RW, in which a second session (i.e., L/I-2, Data-2 and L/O-2) is recorded in the CD-RW illustrated in FIG. 3A.
FIG. 3C illustrates a state of the CD-RW, in which the last session (i.e., the second session) of the CD-RW illustrated in FIG. 3B is erased. This state is logically the same as the state illustrated in FIG. 3A, however, they are different because erasure signals are recorded in the CD-RW illustrated in FIG. 3C.
At this point, when the last session (i.e., the first session) is erased, the CD-RW achieves the state illustrated in FIG. 3D. In this case, since the signals recorded in the first session and the ROM signals in the PMA are not erased and erasure signals are recorded therein, the disc becomes incapable of recording and reproducing information thereafter.
FIG. 3E illustrates a state in which all information is erased. In this case, the disc also becomes incapable of recording and reproducing information thereafter similarly to the disc illustrated in FIG. 3D.
Thus, these media have drawbacks in that controlling of recording and erasing is difficult, and erasure signals are recorded in the ROM region by mistake, thereby making the media incapable of recording or erasing information.
When performing direct overwriting on a phase change optical information recording medium, information is recorded by allowing the recording layer thereof to achieve an amorphous state and information is erased by allowing the recording layer to achieve a crystallized state. The strength of the reflection signals of the recording layer achieving an amorphous state is called a pit level, and the strength of the reflection signals of the recording layer achieving a crystallized state is called a land level.
Direct overwriting is conventionally performed on a phase change optical information recording medium by applying a writing power (Pw) which is determined according to a γ method described in the Orange Book and which depends on the drive used and an erasure power (Pe) which is determined as a product of the writing power (Pw) and a constant (ε).
According to this method, when the writing power (Pw) is relatively high compared to the optimum value thereof, the erasure power (Pe) also increases. Therefore the direct overwriting is performed while applying an excessive erasure power and thereby the recording layer tends to achieve an amorphous state, resulting in decrease of the land level. Therefore, problems such that jitter increases and durability of the recording layer deteriorates occur.
In contrast, when the writing power (Pw) is relatively low compared to the optimum value thereof, the erasure power (Pe) also lowers, and thereby the previously recorded signals cannot be fully erased. Therefore, a problem in that jitter increases occurs.
As another erasing method, a CW (or physical) erasure method, in which erasure is performed by steady laser irradiation, is described in the Orange Book. However, the optimum erasure power (Peo), which is changed by the OPC (optimization of the writing power) while depending on the optimum writing power (Pwo) which is determined according to the γ method described in the Orange Book, is not proper for the CW erasure power (Pecw). Specifically, the portion on which the CW erasure is performed has deteriorated direct overwriting properties. Therefore, logical erasure methods in which direct overwriting of erasure patterns is performed are used for normal erasure.
In addition, hybrid discs which have a ROM region in a portion thereof, which ROM region is formed by a stamper, will be practically used shortly. When logical erasure is performed on the hybrid discs, direct overwriting is performed on the ROM region thereof, and thereby the hybrid discs become incapable of reproducing information.